145 lines
5.0 KiB
Diff
145 lines
5.0 KiB
Diff
commit 3a6c9a855195e6f6f44ad6dffe2cd4046426ab53
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Author: Masahiko, Yamada <yamada.masahiko@fujitsu.com>
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Date: Wed Nov 25 21:46:26 2020 +0900
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fix for performance improvement of _mx_init_component() function
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diff --git a/src/components/mx/linux-mx.c b/src/components/mx/linux-mx.c
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index 2da406d14..34e6f02c2 100644
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--- a/src/components/mx/linux-mx.c
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+++ b/src/components/mx/linux-mx.c
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@@ -224,26 +224,35 @@ _mx_init_component( int cidx )
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{
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FILE *fff;
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- char test_string[BUFSIZ];
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+ char *path;
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+ int len, pathlen;
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/* detect if MX available */
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- strncpy(mx_counters_exe,"mx_counters 2> /dev/null",BUFSIZ);
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- fff=popen(mx_counters_exe,"r");
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- /* popen only returns NULL if "sh" fails, not the actual command */
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- if (fgets(test_string,BUFSIZ,fff)==NULL) {
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- pclose(fff);
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- strncpy(mx_counters_exe,"./components/mx/utils/fake_mx_counters 2> /dev/null",BUFSIZ);
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- fff=popen(mx_counters_exe,"r");
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- if (fgets(test_string,BUFSIZ,fff)==NULL) {
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- pclose(fff);
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- /* neither real nor fake found */
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- strncpy(_mx_vector.cmp_info.disabled_reason,
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- "No MX utilities found",PAPI_MAX_STR_LEN);
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- return PAPI_ECMP;
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+ path = getenv("PATH");
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+ pathlen = strlen(path);
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+ while(pathlen > 0) {
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+ len = strcspn(path, ":");
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+ strncpy(mx_counters_exe, path, len);
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+ mx_counters_exe[len] = '\0';
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+ strcat(mx_counters_exe, "/mx_counters");
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+ fff = fopen(mx_counters_exe, "r");
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+ if (fff != NULL) {
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+ strcat(mx_counters_exe, " 2> /dev/null");
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+ break;
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}
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+ pathlen = pathlen - len - 1;
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+ if (pathlen > 0) {
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+ path = path + len + 1;
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+ }
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+ }
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+ if (fff == NULL) {
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+ /* neither real nor fake found */
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+ strncpy(_mx_vector.cmp_info.disabled_reason,
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+ "No MX utilities found",PAPI_MAX_STR_LEN);
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+ return PAPI_ECMP;
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}
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- pclose(fff);
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+ fclose(fff);
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num_events=MX_MAX_COUNTERS;
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_mx_vector.cmp_info.num_native_events=num_events;
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commit 3a2560a86be44f4b15d96a45eda8e7f387b9166c
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Author: Masahiko, Yamada <yamada.masahiko@fujitsu.com>
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Date: Tue Jan 26 16:30:40 2021 +0900
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Add string length check before strncpy() and strcat() calls in _mx_init_component()
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Myrinet Express-related component MX modules are initialized with the _mx_init_component() function,
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which is called from the PAPI_library_init() function.
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The popen(3) call runs a loadable module called "mx_counters",
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and if the loadable module does not exist,
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it attempts to run a loadable module called "./components/mx/utils/fake_mx_counters".
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In an environment where there are no "mx_counters" and "./components/mx/utils/fake_mx_counters" loadable modules,
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popen(3) will be called twice uselessly.
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popen(3) internally calls pipe(2) once, fork(2) twice and exec(2) once.
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The size of the user space of the application calling the PAPI_library_init() function affects the performance of fork(2),
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which is called as an extension of popen(3).
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As a result, the performance of the PAPI_library_init() function is affected by the amount of user space in the application
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that called the PAPI_library_init() function.
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In the _mx_init_component() function,
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the MX module only needs to be able to verify that a load module named "mx_counters" exists.
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We improved the _mx_init_component() function to call fopen(3) instead of popen(3).
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We add string length check before strncpy() and strcat() calls in _mx_init_component() function.
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diff --git a/src/components/mx/linux-mx.c b/src/components/mx/linux-mx.c
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index 34e6f02c2..c2920d65b 100644
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--- a/src/components/mx/linux-mx.c
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+++ b/src/components/mx/linux-mx.c
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@@ -225,7 +225,7 @@ _mx_init_component( int cidx )
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FILE *fff;
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char *path;
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- int len, pathlen;
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+ int checklen, len, pathlen;
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/* detect if MX available */
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@@ -233,13 +233,31 @@ _mx_init_component( int cidx )
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pathlen = strlen(path);
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while(pathlen > 0) {
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len = strcspn(path, ":");
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- strncpy(mx_counters_exe, path, len);
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+ if (len < BUFSIZ) {
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+ strncpy(mx_counters_exe, path, len);
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+ } else {
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+ fff = NULL;
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+ break;
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+ }
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mx_counters_exe[len] = '\0';
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- strcat(mx_counters_exe, "/mx_counters");
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+ checklen = len + strlen("/mx_counters");
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+ if (checklen < BUFSIZ) {
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+ strcat(mx_counters_exe, "/mx_counters");
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+ } else {
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+ fff = NULL;
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+ break;
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+ }
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fff = fopen(mx_counters_exe, "r");
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if (fff != NULL) {
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- strcat(mx_counters_exe, " 2> /dev/null");
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- break;
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+ checklen = checklen + strlen(" 2> /dev/null");
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+ if (checklen < BUFSIZ) {
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+ strcat(mx_counters_exe, " 2> /dev/null");
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+ break;
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+ } else {
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+ fclose(fff);
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+ fff = NULL;
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+ break;
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+ }
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}
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pathlen = pathlen - len - 1;
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if (pathlen > 0) {
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@@ -247,7 +265,7 @@ _mx_init_component( int cidx )
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}
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}
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if (fff == NULL) {
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- /* neither real nor fake found */
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+ /* mx_counters not found */
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strncpy(_mx_vector.cmp_info.disabled_reason,
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"No MX utilities found",PAPI_MAX_STR_LEN);
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return PAPI_ECMP;
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